Method of forming gelatin sheets and surfaces therefor



Patented Sept. 10, 1929.

UNITED STATES PATENT ol-"rlca.

EDOUABD M. KBATZ, OF CHICAGO, ILLINOIS, ASSIGNOR TO IARBENE PRODUCTS CO., OF CHICAGO, ILLINOIS, A CORPORATION OI ILLINOIS.

METHOD OF FORMING GELATIN SHEETS AND SURFACES THEREFOR.

No Drawing. Application flied February 24, 1925, Serial No. 11,385. Renewed January 7, 1928.

This invention relates to a particular type of prepared surface for the formation of transparent paper of gelatin composition thereon.

Hitherto various surfaces have been known and used for forming such sheets. Among the various ones are polished stone or matrix surfaces, metallic surfaces such as zinc, and surfaces formed from cellulose esters, such as nitro-cellulose, cellulose acetate, etc. These surfaces all have their disadvantages. The stone surfaces have but a limited use. The metallic surfaces are apt to corrode and form other blemishes that result in imperfect gela- 16 tin sheets. The cellulosic surfaces are apt to be fragile and to crack when folded or to mar easily. Such surfaces, especially when formed of nitro-cellulose or pyroxyline materials, have a tendency to cause gelatin sheets 20 containing softening oils to become milky or cloudy due to the action of the nitro-cellulose materials on the softening oils. Moreover, difliculty is often experienced in stripping the finished gelatin from any of the above surfaces due to a tendency of the sheet to adhere to the surface.

It is an object of this invention to provide a prepared surface of durable qualities upon which to form gelatin sheets and from which such sheets may be easily stripped.

It is a further object of this invention to provide a prepared surface suitable for use in combination with a flexible base that will have good flexible and folding qualities.

Other and further important objects of this invention will be apparent from the disclosures in the specification and the appended claims.

While the prepared surface may be used 40 in conjunction with a rigid base, as on a fiat table surface, I prefer to use it in conjunction with a flexible endless belt, since this use is best adapted for production purposes.

The surface which I have found best adapted for use in forming gelatin sheets is that afforded by a waterproof coating for textiles, consisting largely of linseed oil and other blended oils. The fabric used as a base for this surface is a thin English muslin which has been bleached, shrunk and dyed. To this muslin fabric are applied by means of a doctor,- base coats of pigments suspended in drying oils. The coated fabric is then festooned and baked at 180 F. Extra care must be taken to see that the first coat applied to the fabnc is properly anchored. The fabric is then calendered to smooth out the surface. Successive base coats are applied until a relatively smooth surface is obtained. Then several coats of linseed and other blended oils are applied by means of a doctor, and between each successive coat the material is festooned and baked, until a perfectly smooth glazed surface is obtained. The oils used for glaz- .ing are centrifuged or filtered to remove any foreign matter that might cause pimples or other rough places in the finished surface. This surface is now smooth, durable, has excellent folding qualities and is not easily cracked. On account of the thinness of the fabric, it has the property of contracting with the gelatin sheet as the gelatin sheet contracts. This results in a denser, stronger sheet than would be possible if a rigid, non-contracting base were used, since in this latter case the gelatin sheet has a tendency to pull awa from the base in contracting during the rying, and thus to weaken the sheet through the internal stresses set up by the contraction of the gelatin. v

However, the surface need not be smooth but may be impressed with any desired design, since the qualities of the coating are such that there is no tendency of the gelatin sheet to stick to the surface during the stripping process. If a coating havin a stamped design is used, the design is faith ully reproduced on the gelatin sheet.

The methods of forming the gelatin sheets on such a prepared surface as above described are many, but I prefer to use the surface in connection with the process and apparatus described in my copending application for transparent paper and a rocess of manufacture, S. N. 10,962, filed ebruary 21, 1925. According to that process, a elatm composition comprising approximate y 60% to 85% glue and 15% to 40% sulphonated castor oil 1s employed.

In connection with suitable apparatus a 9 warm gelatin sul honated oil com tion solution is a pli to an endless be t made from the fabric material havinglthis prepared surface. After the gelatinfilm asbeen 1el1ed and dried to harden it, it is stripped from the surface by any suitable means. The striping process is much more satisfactory than itherto when other surfaces were used. In this way and with this prepared surface, very thin, perfectly clear,' unblemished gelatin sheets may be prepared.

I am aware that many changes may be made, and-numerous details of the method may be varied through a wide range without departing from the principles of this invention, and I therefore do not pur ose limiting the patent ranted hereon, ot erwise than necessitated y the prior art.

I claim as my invention:

1. 'A surface for forming gelatin sheets containin sulphonated oil, largely comprised of linsee oil and other blended oils.

2. The method of preparing sheets of gelatin-sulphonated oil compositlon, comprlsing spreading a solution of said composition over a surface com rising a preparation of linseed oil and other lended oils, cooling such solution to allow the composition to jell, d ing and then stripping the sheet so formed rom such surface.

3. The method of preparing gelatin sheets containing sulphonated oil, comprising applying a gelatin and sul honated oil solution to a surface comprising argely a preparation of drying oils, allowing the solution to harden, drying and then stripping the sheet so formed from said surface.

4. In combination with a machine for making transparent pa er of gelatin and sulphonated oil composition, a sheet forming surface comprising a web of thin fabric material having a coating of baked drying oils adhering thereto.

5. Web material for use in the formation of gelatin composition, transparent sheets, comprising a fa ric having a coating thereon of baked drying oils on which said sheets may be formed andfrom which said sheets may be readily stripped when d In testimony whereof I have hereunto subscribed my name.

EDOUARD M. KRATZ. 

